Coupling in and to rfid smart cards

ABSTRACT

A dual interface (DI) smart card ( 100 ) comprising a chip module (CM), a module antenna (MA), a card body (CB) and a card antenna (CA) having two windings (D,E) connected with reverse phase as a “quasi-dipole”. Capacitive stubs (B,C) connected with an antenna structure (A) of the module antenna (MA). The module antenna (MA) overlaps only one of the windings (D or E) of the card antenna (CA). The card antenna (CA) may be formed from one continuous wire. Ferrite ( 156 ) shielding the module antenna (MA) from contact pads (CP) and for enhancing coupling between the module antenna (MA) and the card antenna (CA).

TECHNICAL FIELD

The invention relates to “secure documents” such as electronicpassports, electronic ID cards and smart cards having RFID (radiofrequency identification) chips or chip modules and operating in acontactless mode (ISO 14443) including dual interface (“DI”, or “DIF”)cards which can also operate in contact mode (ISO 7816-2), and moreparticularly to improving coupling between components within the smartcard, such as between a module antenna (MA) associated with the chipmodule (CM) and a card antenna (CA) on the card body (CB) of the smartcard and consequent improvements in interacting with external RFIDreaders.

BACKGROUND

For purposes of this discussion, an RFID transponder generally comprisesa substrate, an RFID chip (or chip module) disposed on or in thesubstrate, and an antenna disposed on or in the substrate. Thetransponder may form the basis of a secure document such as anelectronic passport, smart card or national ID card.

The chip module may operate solely in a contactless mode (such as ISO14443), or may be a dual interface (DIF) module which can operate alsoin contact mode (such as ISO 7816-2) and a contactless mode. The chipmodule may harvest energy from an RF signal supplied by an external RFIDreader device with which it communicates.

The substrate, which may be referred to as an “inlay substrate” (forelectronic passport) or “card body” (for smart card) may comprise one ormore layers of material such as Polyvinyl Chloride (PVC), Polycarbonate(PC), polyethylene (PE), PET (doped PE), PET-G (derivative of PE),Teslin™, Paper or Cotton/Noil, and the like. When “inlay substrate” isreferred to herein, it should be taken to include “card body”, and viceversa, unless explicitly otherwise stated.

The chip module may be a leadframe-type chip module or an epoxy-glasstype chip module. The epoxy-glass module can be metallized on one side(contact side) or on both sides with through-hole plating to facilitatethe interconnection with the antenna. When “chip module” is referred toherein, it should be taken to include “chip”, and vice versa, unlessexplicitly otherwise stated.

The antenna may be a self-bonding (or self-adhering) wire. Aconventional method of mounting an antenna wire to a substrate is to usea sonotrode (ultrasonic) tool which vibrates, feeds the wire out of acapillary, and embeds it into or sticks it onto the surface of thesubstrate. A typical pattern for an antenna is generally rectangular, inthe form of a flat (planar) coil (spiral) having a number of turns. Thetwo ends of the antenna wire may be connected, such as bythermo-compression (TC) bonding, to terminals (or terminal areas, orcontact pads) of the chip module. See, for example U.S. Pat. No.6,698,089 and U.S. Pat. No. 6,233,818, incorporated by reference herein.

A problem with any arrangement which incorporates the antenna into thechip module (antenna module) is that the overall antenna area is quitesmall (such as approximately 15 mm×15 mm), in contrast with a moreconventional antenna which may be formed by embedding several (such as 4or 5) turns of wire around a periphery of the of the inlay substrate orcard body of the secure document, in which case the overall antenna areamay be approximately 80 mm×50 mm (approximately 20 times larger). Whenan antenna is incorporated with the chip module, the resulting entitymay be referred to as an “antenna module”.

SOME STATE OF THE ART

The following patents and publications are incorporated in theirentirety by reference herein.

U.S. Pat. No. 5,084,699 (Trovan, 1992) entitled Impedance Matching CoilAssembly For An Inductively Coupled Transponder. Attention is directedto FIG. 5. A coil assembly for use in an inductively powered transponderincludes a primary coil (156) and a secondary coil (158) wrapped aroundthe same coil forming ferrite rod (160). The primary coil's leads (162)are left floating while the secondary coil's leads (164) are connectedto the integrated identification circuit of the transponder.

U.S. Pat. No. 5,955,723 (Siemens, 1999) entitled Contactless Chip Carddiscloses a data carrier configuration includes a semiconductor chip.Attention is directed to FIG. 1. A first conductor loop (2) is connectedto the semiconductor chip (1) and has at least one winding and across-sectional area with approximately the dimensions of thesemiconductor chip. At least one second conductor loop (3) has at leastone winding, a cross-sectional area with approximately the dimensions ofthe data carrier configuration and a region forming a third loop (4)with approximately the dimensions of the first conductor loop (2). Thethird loop (4) inductively couples the first conductor loop (2) and theat least one second conductor loop (3) to one another.

U.S. Pat. No. 6,378,774 (Toppan, 2002) entitled IC Module and SmartCard. Attention is directed to FIGS. 12A,B and 17A,B. A smart cardcomprises an IC module and an antenna for non-contact transmission. TheIC module has both a contact-type function and a non-contact-typefunction. The IC module and the antenna comprise first and secondcoupler coils, respectively, which are disposed to be closely coupled toeach other, and the IC module and the antenna are coupled in anon-contact state by transformer coupling.

Toppan's antenna (4) comprises two similar windings (4 a, 4 b), whichare shown in FIG. 17A disposed on opposite sides of a substrate (5), onesubstantially atop the other. A coupler coil (3) is associated with thecard antenna (4). Another coupler coil (8) is associated with the chipmodule (6). As best viewed in FIGS. 12A and 12B, the two coupler coils(3, 8) are of approximately the same size and are disposed substantiallyone atop the other.

U.S. Pat. No. 7,928,918 (Gemalto, 2011) entitled Adjusting ResonanceFrequency By Adjusting Distributed Inter-Turn Capacity discloses amethod for adjusting frequency tuning of a resonant circuit with turnshaving a regular spacing generating stray inter-turn capacity.

US 2009/0152362 (Assa Abloy, 2009) discloses Coupling Device ForTransponder And Smart Card With Such Device. Attention is directed toFIG. 6. A coupling device is formed by a continuous conductive pathhaving a central section (12) and two extremity sections (11, 11′), thecentral section (12) forming at least a small spiral for inductivecoupling with the transponder device, the extremities sections (11, 11′)forming each one large spiral for inductive coupling with the readerdevice.

Assa Abloy shows that the inner end of the outer extremity section (11)and the outer end of the inner extremity section (11′) are connectedwith the coupler coil (12). The outer end (13) of the outer extremitysection (11) and the inner end (13′) of the inner extremity section(11′) are left unconnected (loose).

US2010/0176205 (SPS, 2010) entitled Chip Card With Dual CommunicationInterface. Attention is directed to FIG. 4. A card body (22) includes adevice (18) for concentrating and/or amplifying electromagnetic waves,which can channel the electromagnetic flow received, in particular, froma contactless chip card reader toward the coils of the antenna (13) ofthe microelectronic module (11). The device (18) for concentratingand/or amplifying electromagnetic waves may consist of a metal sheetdisposed in the card body (22) below the cavity (23) receiving themicroelectronic module (11), or may consist of an antenna consisting ofat least one coil, disposed in the card body (22) below the cavity (23)receiving the microelectronic module (11).

Refer also to the following: CA 2,279,176; DE 4311493; U.S. Pat. No.6,142,381; U.S. Pat. No. 6,310,778; U.S. Pat. No. 6,406,935; U.S. Pat.No. 6,719,206; US 2009/0057414; US 2010/0283690; and US 2011/0163167.

SUMMARY

A dual interface (DI) smart card (100) comprising a chip module (CM), amodule antenna (MA), a card body (CB) and a card antenna (CA) having twowindings (D,E) connected with reverse phase as a “quasi-dipole”.Capacitive stubs (B,C) connected with an antenna structure (A) of themodule antenna (MA). The module antenna (MA) overlaps only one of thewindings (D or E) of the card antenna (CA). The card antenna (CA) may beformed from one continuous wire. Ferrite (156) shielding the moduleantenna (MA) from contact pads (CP) and for enhancing coupling betweenthe module antenna (MA) and the card antenna (CA).

A dual interface (DIF) smart card comprises

-   -   a generally rectangular card body CB which may be of multi-layer        construction, measuring approximately 50 mm×80 mm,    -   a DIF chip module CM measuring approximately 8 mm×10 mm, having        metallic contact pads (CP) one side of the chip module CM and a        module antenna MA on the other side of the chip module CM, and    -   a card antenna CA extending around the periphery of the card        body CB and having approximately the same overall size as the        card body CB.

The module antenna MA has a number of turns in a flat spiral pattern,may be rounded, oval or generally rectangular having four side edges,and may be substantially the same overall size as the chip module CM.The module antenna may comprise a wire element wound as a flat coil, ormay be etched in a flat coil pattern from a conductive layer on aninsulating layer (such as epoxy glass film, or tape).

The card antenna CA may comprise two windings (or coils)—an outerwinding D, and an inner winding E disposed interior of the outer windingD. The inner E and outer D windings are of substantially the same lengthas each other, each have two ends (or positions) 7, 8, 9, 10 and areconnected to have “reverse phase” as a “quasi dipole”. For example, theouter end (7) of the outer winding D is connected (or continuous) withthe inner end 10 of the inner winding E.

The card antenna CA may be formed by conventional wire embedding, orusing techniques other than wire embedding such as additive orsubtractive processes to form conductive tracks and patterns.

The antenna module AM is disposed so that its module antenna MA overlapsone of the inner E or outer D windings, and not the other. No separatecoupling coil is required to couple the module antenna MA with the cardantenna CA. Various configurations for the card antenna CA aredisclosed, such as

-   -   the antenna module AM is disposed interior the card antenna CA,        and the module antenna MA overlaps only the inner winding E.    -   the antenna module AM may be disposed exterior the card antenna        CA with its module antenna MA overlapping only the inner winding        E, or interior the card antenna CA with its module antenna MA        overlapping on the outer winding D.    -   additional one or more antenna modules AM1, AM2 may be provided        and coupled with the card antenna CA to provide additional        functionality    -   the card antenna CA may alternatively be formed as a single        winding which may require many more turns than the “quasi        dipole” (two windings D, E connected with “reverse phase”)

To alleviate adverse effects of the metallic contact pads CP on couplingbetween the module antenna MA and the card antenna CA, a shieldingelement such as ferrite may be incorporated in the antenna module AMbetween the module antenna MA and the contact pads CP of the chip moduleCM.

The module antenna MA may comprise a “main” antenna structure A and twoadditional antenna structures B, C which are capacitive stubs extendingfrom ends of the antenna structure A.

The antenna module AM may be incorporated in a secure document such asan electronic passport cover, smart card, ID card, or the like.

According to some embodiments of the invention, a smart card (100)comprises:

-   -   an antenna module (AM) comprising at least one chip or chip        module (CM) and a module antenna (MA);    -   a card body (CB) having at least one surface and a periphery;        and    -   a card antenna (CA) extending around the periphery of the card        body (CB);    -   characterized in that at least a portion of the module antenna        (MA) overlaps at least a portion of the card antenna (CA) for        coupling thereto without the intermediary of a coupling coil        associated with the card antenna (CA).

According to some embodiments of the invention, a method of coupling achip module (CM) having at least a contactless mode to a card antenna(CA) disposed on a card body (CB) of a smart card, comprising providinga module antenna (MA) in an antenna module (AM) with the chip module(CM), characterized by: providing the card antenna (CA) as “quasidipole” antenna having two winding portions connected in reverse phasewith one another. The card antenna (CA) may have an inner winding (E)and an outer winding (D); and the module antenna (MA) overlaps only oneof the inner and outer windings (E, D).

A pre-laminated array of a special antenna configuration used in theproduction of contact & contactless transaction cards. In application,the card antenna sandwiched between the outer layers and the printedlayers of a smart card, electromagnetically couples with an implantedantenna module AM in the card body CB, achieving a read/write rangesuperior to existing DIF technology. This method of transceiving data isalso a major advancement over the unreliable interconnection between achip card module and an embedded antenna in a card body.

Secure printers can use their existing smart card milling and chipmodule implanting systems to produce EMV (Europay, MasterCard and VISA)compatible dual interface cards. Some features may include differentsheet layouts to match printing press format, read/write distanceoptimized to each RFID chip, excellent mechanical and electricalcharacteristics, and easy integration into existing smart cardproduction process.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will be made in detail to embodiments of the disclosure,non-limiting examples of which may be illustrated in the accompanyingdrawing figures (FIGs). The figures are generally diagrams. Someelements in the figures may be exaggerated, others may be omitted, forillustrative clarity. Although the invention is generally described inthe context of various exemplary embodiments, it should be understoodthat it is not intended to limit the invention to these particularembodiments, and individual features of various embodiments may becombined with one another.

FIGS. 1A, 1B are cross-sectional views of DIF smart cards, according tothe invention.

FIG. 1C is a cross-sectional view of a coil subassembly for an antennamodule (AM) of a smart card, according to the invention.

FIG. 1D is a cross-sectional view of a DIF smart card, according to theinvention.

FIG. 1E is a cross-sectional view of a DI chip module, according to theinvention.

FIG. 2A is a schematic diagram of an antenna module (AM), according tothe invention.

FIG. 2B is a cross-sectional view diagram of the antenna module (AM) ofFIG. 2A.

FIG. 3A is a diagram of a card antenna (CA) for a smart card, accordingto the invention.

FIG. 3B is an equivalent circuit diagram of reactive components(capacitances and inductances) associated with the card antenna (CA) ofFIG. 3A.

FIG. 4A is a diagram (plan view) of a configuration of a card antennaCA, according to some embodiments of the invention.

FIG. 4B is a cross-sectional view of the configuration shown in FIG. 4A.

FIGS. 4C, 4D, 4E, 4F, 4G, 4H are diagrams (plan view) of configurationsof a card antenna CA, according to some embodiments of the invention.

FIGS. 4I, 4J are cross-sectional views of smart cards withconfigurations of a card antenna (CA), according to some embodiments ofthe invention.

FIGS. 5A, 5B, 5C, 5D, 5E, 5F, 5G, 5H are diagrams (plan view) of variousconfigurations for the card antenna (CA) and various means ofinteracting with one or more antenna modules AMs, according to someembodiments of the invention.

FIG. 6A is a cross-sectional view of a technique for applying a mobilephone sticker (MPS) to a cell phone, and FIG. 6B is a cross-sectionalview of a shielding element used in the technique for applying a mobilephone sticker (MPS) to a cell phone, according to some embodiments ofthe invention.

FIGS. 7A, 7B, 7C, 7D are perspective views of steps involved in a methodfor making antenna modules (AMs), according to some embodiments of theinvention.

FIG. 7E is a perspective view of a smart card implementing some of theembodiments of the invention disclosed herein. FIG. 7F is a perspectiveview of a portion of a card body CB with an antenna wire passing througha recess for an antenna module AM.

DETAILED DESCRIPTION

Various embodiments will be described to illustrate teachings of theinvention(s), and should be construed as illustrative rather thanlimiting. In the main hereinafter, transponders in the form of securedocuments which may be smart cards or national ID cards may be discussedas exemplary of various features and embodiments of the invention(s)disclosed herein. As will be evident, many features and embodiments maybe applicable to (readily incorporated in) other forms of securedocuments, such as electronic passports.

In the main hereinafter, antenna structures formed by embedding wire inan inlay substrate or card body are discussed as exemplary. However, itshould be understood that the antenna may be formed using a processesother than by embedding wire in a substrate, such as additive orsubtractive processes such as printed antenna structures, coil windingtechniques (such as disclosed in U.S. Pat. No. 6,295,720), antennastructures formed on a separate antenna substrate and transferred to theinlay substrate (or layer thereof), antenna structures etched (includinglaser etching) from a conductive layer on the substrate, conductivematerial deposited in channels of a substrate layer, or the like.

The descriptions that follow are mostly in the context of dual interface(DI, DIF) smart cards, and relate mostly to the contactless operationthereof. Many of the teachings set forth herein may be applicable toelectronic passports and the like having only a contactless mode ofoperation. Generally, any dimensions set forth herein are approximate,and materials set forth herein are intended to be exemplary.

By coupling, rather than connecting the chip module CM with the cardantenna CA, the “weak link” of a physical connection between a chipmodule CM and a card body antenna (such as in U.S. Pat. No. 7,980,477)is eliminated. However, coupling is much more challenging to accomplishthan a direct physical connection. Therefore, effective coupling betweenthe module antenna MA and the card antenna CA and consequently to theantenna of a contactless reader is important.

The card antenna CA (and other features) disclosed herein may increasethe effective operative distance between the antenna module AM and anexternal contactless reader with capacitive and inductive coupling. Ittransfers the energy to the antenna module AM by concentrating themagnetic field generated by a reader antenna at the position where theantenna module AM is located.

FIG. 1A illustrates a DIF smart card comprising:

-   -   a DIF chip module CM disposed on an underside of a substrate or        module tape MT;    -   a number (such as six) of contact pads CP for implementing a        contact interface (ISO 7816) on a top side of the module tape        MT; and    -   a module antenna (MA) disposed on the underside of the module        tape (MT), typically formed from an etched conductor or wire, in        a spiral (coil) pattern.    -   The substrate MT supports and effects interconnections between        the chip module CM, contact pads CP and module antenna MA, and        may be single-sided, having metallization on only one side, or        double-sided, having metallization on both sides.    -   The chip module CM may be connected in any suitable manner, such        as flip-chip connected (as illustrated in FIG. 1A) or wire        bonded (as illustrated in FIG. 1B to the module tape MT.    -   As used herein, “chip module” includes one or more bare        semiconductor dice (chips). A “hybrid” chip module may comprise        a chip for contact interface and a chip for contactless        interface, or the like. Reference is made to U.S. Pat. No.        6,378,774 (Toppan, 2002) for an example of a DIF chip solution,        and to US 2010/0176205 (SPS, 2010) for an example of a two chip        solution wherein one chip performs the contact function and the        other chip performs the contactless function.    -   Together, the chip module, CM, chip tape MT, contact pads CP and        module antenna MA constitute an “antenna module” AM.

The smart card further comprises:

-   -   a substrate which for smart cards may be referred to as a “card        body” CB. (For an electronic passport, the substrate would be an        “inlay substrate”.)    -   a card body antenna (CBA), or simply card antenna (CA) disposed        around the periphery of the card body, typically in the form of        a rectangular, planar spiral having a number of turns.    -   As used herein, card body CB is intended to embrace any        substrate supporting card antenna CA and receiving the antenna        module AM. A recess may be provided in the card body for        receiving the antenna module AM.

Some exemplary and/or approximate dimensions, materials andspecifications may be:

-   -   Module Tape (MT): epoxy-based tape, 60 μm thick    -   Chip Module (CM): NXP SmartMx or Infineon SLE66, or other    -   Antenna Module (AM): 15 mm×15 mm and 300 μm thick    -   Module Antenna (MA): several windings of 50 μm copper wire,        approximately the size of the chip module CM (and not greater in        size then the AM)    -   Card body CB: 50 mm×80 mm, 300 μm thick, polycarbonate (PC). The        card body and its card antenna are significantly (such as 20        times) larger than the chip module CM and its module antenna MA.    -   Card Antenna CA: 3-12 turns of 112 μm copper, self-bonding wire,        ultrasonically embedded in the card body CB,

Additional layers (not shown), such as cover layers, may be laminated tothe card body to complete the construction of the smart card.

FIG. 1A illustrates a contact reader having contacts for interacting(providing power and exchanging data) with the chip module CM via thecontact pads CP in a contact mode (ISO 7316), and a contactless readerhaving an antenna for interacting with the chip module CM via the cardantenna CA and the module antenna MA.

FIG. 1B illustrates (exploded view) an overall construction of a DIFsmart card 100 comprising

-   -   an epoxy glass substrate (MT) 102 having a number of contact        pads (CP) 104 on its top (as viewed) surface for making a        contact interface with an external reader in a “contact mode” of        operation;    -   a number of bond pads 106 disposed on an opposite surface of the        tape 102;    -   a DIF chip module (CM) 108 having a number (only two shown) of        bond pads 110 on a front (bottom, as viewed) surface thereof;    -   a module antenna (MA) 112 comprising (for example) several turns        of wire, such as in a 3×8 configuration (3 layers, each layer        having 8 turns), and having two ends 112 a and 112 b.

The chip module 108 may be mounted to the underside (as viewed) of thetape 102 with its contact pads 110 connected such as by conventionalwire bonding to selected ones of the bond pads 106 on the underside (asviewed) of the tape 102. Only two of the wire bond connections 114 a and114 b are shown, for illustrative clarity.

The module antenna 112 is connected by its ends 112 a, 112 b such as bethermo compression bonding to two of the bond pads 106 on the undersideof the tape 102, as indicated.

The aggregate of the elements described above, generally the module tape102, chip module 108 and module antenna 112 may be referred to as an“antenna module” 118.

A card body (CB) 120 for the smart card has a larger card antenna (CA)122 embedded just inward of its periphery. The module antenna 112couples (electro-magnetically) with the card antenna 122 to improvecoupling of the smart card with an external contactless reader. The cardantenna 122 may be formed on the card body 120 using conventionalultrasonic wire embedding techniques.

To enhance coupling between the module antenna 112 and the card antenna122, a material exhibiting electromagnetic coupling properties, such asferrite, may be disposed as a thin film 124 on surface of the card body120 or may be incorporated or embedded as particles 126 in the card body120, or both (film and particles), in any desired pattern.

The use of ferrite as a material to enhance coupling or to shield(prevent) coupling is discussed herein as exemplary of a materialexhibiting high electromagnetic permeability, often being used in oneform or another in conjunction with antennas. See, for example, U.S.Pat. No. 5,084,699 (Trovan).

Coil Antenna Subassembly for a DIF Chip Module

FIG. 1C illustrates a construction of a coil sub-assembly 130 for asmart card such as the DIF smart card 100 of FIG. 1B. A coil of wire 112for the module antenna (MA) may be wound, using any suitablecoil-winding tool, and disposed on a film support layer 132.

The module antenna MA may comprise several turns of wire, such as in a3×8 configuration (3 layers, each layer having 8 turns), and having twoends 112 a, 112 b. The wire may have a diameter of approximately 80 μm,the resulting module antenna 112 having an overall thickness (or height)of approximately 240 μm (3×80 μm). The module antenna MA may be in theform of a ring (cylinder), having an inner diameter (ID) ofapproximately 9 mm, and an outer diameter of approximately 10 mm.

The film support layer 132 may be nitrile film, 60 μm thick and haveoverall outer dimensions of approximately 10-15 mm×10-15 mm, orapproximately twice as large (across, in one dimension) as the moduleantenna MA which will be mounted thereto.

A central opening 134 is provided through the film 132, generallyaligned with the position of the module antenna MA, and having adiameter which is nearly as large as the ID of the module antenna MA.The opening 134 may be formed by a punching operation. The opening 134is for accommodating a chip module (such as 108) and its wire bonds whenthe antenna module AM is assembled.

Two openings 136 a and 136 b may be provided (in the same punchingoperation as the central opening 134) through the film 132 foraccommodating bonding of the antenna wire ends 112 a and 112 b,respectively, to the bond pads (106, FIG. 1B) on the module tape MT(102).

A release liner 138 may be provided on one side of the film 132, such asthe side opposite the module antenna MA. The central opening 134 may ormay not extend through the release liner 138, which may be paper, havinga thickness of approximately 60 μm.

The module antenna MA may be secured to the support film 132 with anadhesive (not shown), resulting in what may be referred to as a “moduleantenna subassembly”. A plurality of module antenna subassemblies may beprepared in an array (m×n rows and columns) of subassemblies, or on acontinuous tape (1 long row) for later assembly, such as by laminating,to the module tape MT. (Invert the subassembly shown in FIG. 1C, mountto the module tape 102 shown in FIG. 1B.) The chip module (108) may thenbe mounted through the central opening in the module antenna MA to themodule tape (102) and connected to the bond pads (106) on the moduletape as described hereinabove.

An alternative to using the “double sided” module tape MT—so calledbecause it has metallic pads on both sides (and internal conductivevias), the module tape may be “single sided” having only metallizationon side thereof, such as for the contact pads CP. For a single sidedtape, openings would extend from the chip module side of the tape tounderneath the back sides of the contact pads CP, for connectingthereto. (The module antenna connections can also be effected in thismanner, to the exposed back surfaces of selected ones of the contactpads.)

Another DIF Smart Card

FIG. 1D illustrates an exemplary dual interface (DIF) smart card 140wherein a DIF chip module (CM) 148 is mounted to an interconnectionsubstrate (MT) 142 having contact pads (CP) 144 for a contact interfaceon one surface (top, as shown) thereof. A coil antenna (MA) 152 isprovided for contactless mode, and is connected to the chip module CMvia the substrate MT. The module antenna MA is typically on an oppositeside (bottom, as shown) of the chip module CM than the contact pads CP.Together, the substrate MT, chip module CM, contact pads CP and coilantenna MA (and ferrite element 156, described below) may be referred toas “Antenna Module” (AM).

The Antenna Module (AM) is mounted to a card body (CB) 160 having a cardantenna (CA) 162. In the contactless mode, the module antenna (MA) 152interacts with the card antenna (CA) 162 which, in turn interacts withthe antenna (not shown) of an external reader (not shown). Someparticulars may include . . .

-   -   the antenna module and module antenna are relatively small, such        as 10 mm×10 mm    -   the card body and card antenna are relatively large, such as 50        mm×80 mm    -   the module antenna may be substantially directly over a portion        of the card antenna (as shown in the figure), the remainder of        the card antenna may be distant from the chip module and module        antenna.    -   the card antenna may be made with conductive tracks or the like,        in other words other than by embedding wire, which is the        simplest “conventional” technique.

The contact pads CP on the top side of the DIF module are metallic, andtherefore may attenuate RF signals passing between the module antenna MAand the card antenna CA. In order to alleviate the attenuation, and toenhance coupling between the module antenna and the card antenna (andultimately between the chip module and an external reader), a ferriteelement (FE) 156 may be disposed (interposed, inserted) between the chipmodule and the module antenna—or, in other words, between the contactpads (CP) 144 and the module antenna (MA) 152.

The ferrite element FE may cover an area which is at least 50% of thearea defined by the chip and antenna, or by the contact pads andrepresents a passive magnetic element that may increase electromagneticcoupling between the module antenna MA and the card antenna CA,providing for example at least a +3 dB increase in signal strength (forsignals passing between the module antenna MA and the card antenna CA,in either direction) and a consequent increase in the effective distancebetween the smart card 140 and an external contactless card reader (FIG.1A), for example increasing read/write (and energy harvesting)capability from approximately 3-5 cm to approximately 6-10 cm.

The ferrite element 156 may be a separate layer of material, such fromTDK or Kitagawa (see http://www.kitagawa.de/index.php?id=8&L=1). Theferrite element 156 may be sprayed onto the bottom surface of the chipmodule prior to installing the module antenna. The ferrite element 156may be continuous (or contiguous, except for openings permittingconnecting the antenna module through the ferrite element to the chipmodule), or may be discontinuous (for example, a grid or screen). Asillustrated, an opening 158 in the ferrite element/layer 156 may beprovided for the chip module CM to be mounted to the substrate 142. Theferrite element 156 may have a smooth surface, or may be rippled, orformed with a pattern of “corner reflectors” for enhancing couplingbetween the module antenna MA and the card antenna CA. The ferriteelement 156 may comprise nanostructures such as nanoparticles, nanowiresor nanotubes. The ferrite (or other) element 156 may be located otherthan between the module antenna MA and the chip module CM (contact padsCP), so long as the desired effect is achieved. Materials other thanferrite may be used for the “ferrite element”. Any material, such asmaterials with high electromagnetic permeability, increasing thecoupling (efficiency of energy transfer) between the module antenna MAand the card antenna CA may be substituted for ferrite.

The chip module of FIG. 1B may be implanted in a card body CB which maycomprise a die attached and wire bonded to an epoxy glass tape and theconnections encapsulated by a dam filled with a transparent UV-castingcompound (epoxy resin) having a thickness above the tape ofapproximately 400 μm. The shape of the “Dam & Fill” area protecting thesilicon die is round, having approximately a diameter of 6 mm. A ferriteelement FE is mounted over the surface of the dam and surrounding areato act as a shield against the attenuation of the electromagnetic field.The wire module antenna MA is mounted onto the ferrite layer and thewire ends are connected by means of thermo compression bonding to theterminal areas on the epoxy glass tape.

In an alternative construction, the chip module CM may comprise a chiphaving its own antenna (such as in U.S. Pat. No. 6,373,447), eitherdirectly coupled with the card antenna CA (without a module antenna MA)or coupled with the module antenna (AM) which is coupled with the cardantenna.

FIG. 1E illustrates a conventional dual-interface chip module CM whichconnects directly with a card antenna (CA) disposed in a card body (CB).Contact pads (CP) are provided on a top surface of the chip module for acontact interface. Two terminals are provided on the bottom surface ofthe chip module for connecting with the card antenna. A dual-interface(DI) chip may be wire bonded to various contact pads on the tapesubstrate of the chip module. Glob-top may be applied to protect the DIchip and wire bonds.

As discussed herein, a module antenna (MA) may be provided, andincorporated with the chip module, for electro-magnetically coupling thechip module to the card antenna. And, as mentioned above, ferrite may beincorporated into a resulting antenna module (AM) to improve couplingbetween the module antenna and the card antenna.

The module antenna MA may be a flat wound coil disposed on the glob-topmold mass of the chip module (MA).

Commercially-available chip modules (CM) or antenna modules (AM) (suchas NXP SmartMx or Infineon SLE66, or other) can be used in conjunctionwith the present invention(s), either “off the shelf” or with somemodifications that may be disclosed herein, such as adding a moduleantenna MA to a chip module CM, or adding a ferrite element in theresulting antenna module

AM.

Some aspects of the invention(s) that will now be discussed includeimprovements to the module antenna MA (FIGS. 2A, 2B) and improvements tothe card antenna (FIGS. 3A, 3B).

Capacitive Stubs for Module Antenna (MA)

FIGS. 2A, 2B illustrate an embodiment of an antenna module (AM) 200comprising:

-   -   a chip module (CM) 208 having two terminals 208 a, 208 b    -   an inductive wire antenna structure (A) 210 formed as a flat        coil of embedded wire having a number (such as 12) of turns, and        two ends—an outer end 1 (at the end of an outer one of the        turns) and an inner end 2 (at an end of an inner one of the        turns).        -   The overall length of the antenna A may be 400 mm        -   The ends 1 and 2 of the antenna A may be connected to the            terminals of the chip module.        -   The chip module may be disposed within (interior to) the            turns of the antenna A.        -   The outer turn of the antenna A may cross over inner turns            of the antenna A to be routed to the chip module CM.    -   capacitive antenna extensions (or stubs, or “antenna        structures”) B and C also formed as flat coils of embedded wire        having a number of turns, and connected to the inductive wire        antenna as described below.

The chip module 208 and antenna A 210 may be disposed in or on a layer222 of a multi-layer antenna substrate 200. The chip module 208 may bedisposed in a recess (pocket) 206 extending partially through the layer222 (as illustrated), or may be disposed in a recess (opening) extendingcompletely through the layer 222, with the chip module 208 beingsupported by an underlying layer 224.

The chip module is illustrated in FIG. 2B “face up”, with its terminalsfor connecting with the antenna A on its top side. Alternatively, thechip module may be orientated “face down” with its antenna-receivingterminals on its bottom side (and extend through the substrate 222, forexample), and another set of terminals (not shown) for a contactinterface on its top side.

Other variations for the AM 200 may include, but are not limited to . ..

-   -   the antenna A may be on the bottom of the layer 222    -   the stub B 212 may be on the bottom of the layer 224    -   the stub C 214 may be on the bottom of the layer 226    -   the stubs B and C may be on the top and bottom surfaces of a        single layer which is either above or below the layer 222

The stub B 212 may be formed as a flat coil of wire having a number(such as 12) of turns and two ends—an outer end 3 of an outer turn andan inner end 4 of an inner turn—in a layer 224 overlying the layer 222.The stub B may have an overall length of approximately 400 mm, and maybe aligned with (directly over) the antenna A.

The stub C 214 may be formed as a flat coil of wire having a number(such as 12) of turns and two ends—an outer end 5 of an outer turn andan inner end 6 of an inner turn—in a layer 226 underlying the layer 222.The stub C may have an overall length of approximately 400 mm, and maybe aligned with (directly under) the antenna A. The stub C may bealigned with (directly under) the stub B. The stubs B and C may beformed by etching, printing, or other processes, instead of (other than)using embedded wire.

In the schematic view of FIG. 2A, the antenna A and stubs B, C are shownlaterally offset from each other. In FIG. 2B, the inductive wire antennaA and capacitive antenna extensions B and C are shown positioned andaligned atop one another. As best viewed in FIG. 2A, the antennastructures A, B, C may each be formed in a flat coil pattern having anumber of turns, an overall length (from end to end), and a footprint(length×width), and may be substantially identical with one another inthese regards. As best viewed in FIG. 2B, the antenna structures A, B, Cmay be disposed substantially directly over one another.

FIG. 2B illustrates that the number of turns, length, width, pitch andpattern of the stubs B, C may be substantially the same (match) as eachother and they may be aligned one atop the other in layers of theantenna module 200 so that their turns are aligned with one another,turn-for-turn. The stubs B, C may also substantially match and bealigned with the antenna A. Capacitance and the resonant circuit isformed between A+B and A+C. Antenna A is shown disposed in a layerbetween the layers for stubs B and C. Antenna A could alternatively bedisposed in a layer above or below both of the layers for stubs B and C.

Dashed lines (- - -) indicate that the inner end 4 of the stub B 212 maybe connected to the outer end 1 of the antenna A 210, such as at theterminal 208 b, and the outer end 5 of the stub C may be is connected tothe inner end 2 of the antenna A, such as at the terminal 208 b. Theouter end 3 of the stub B and the inner end 6 of the stub C may be leftunconnected (remain open).

Alternatively, the vertical arrows (↓,↑) indicate that the outer end 3of the stub B may be connected to the outer end 1 of the antenna A (suchas at terminal 208 b), and the inner end of stub C may be connected withthe inner end of the antenna A.

Note that in either case, “opposite” (inner versus outer) ends of thestubs B, C are connected to the two ends 1, 2 of the antenna A—in otherwords, the inner end 4 of B and the outer end 5 of C. As used herein,“connected in an opposite sense” means that the inner end of one of thetwo stubs (B or C) is connected with one end of the antenna (A), and theouter end of the other of the two stubs (C or B) is connected with theother end of the antenna (A). It is generally not desirable that the“same” (such as both inner) ends of the stubs are connected with theends of the antenna A. The connections (interconnects) discussed hereincan be made in any conventional manner, such as by vias through layers,traces on layers, bonding, soldering, crimping, welding, etc.

Locating the stubs B and C over each other in close proximity with theantenna A between them forms additional resonant circuits between the Aand the stubs B, C realized by the stray capacitance between the antennastructures A, B, C. The interaction between the coupled stubs B and Cexposed to the same electromagnetic field from the antenna A mayadvantageously reduce the self-resonance (or self-resonant) frequency ofthe antenna A. Stub B is close to antenna A and stub C is close toantenna A, ergo stub B is close to stub C.

In electronics, capacitors and inductors have parasitic inductance andcapacitance, respectively. For a capacitor, the inductance is primarilydue to the physical dimensions including the leads. Since a capacitorand inductor in series creates an oscillating circuit, all capacitorsand inductors will oscillate when stimulated with a step impulse. Thefrequency of this oscillation is the self-resonant frequency (SRF).

The dimensions of the antenna module AM may be approximately 10-15mm×10-15 mm, and it may of course be round, rather than rectangular. Dueto the relatively small available area, an inductive wire loop of thesize of the antenna module may have a self-resonance frequency ofapproximately 75 MHz. The over-layered close-coupled antenna structures(stubs B and C) may function as a wire formed capacitor—with open wireends (3 and 6)—that may reduce the resonance frequency of the formedtransponder to a more desirable value of approximately 13-17 MHz,thereby increasing the voltage and transferred power to the chip module.

This principle of over-layered close-coupled wire (or other conductivetrace) antenna structures (stubs B and C) facilitates reducing the spaceconsumption of the antenna A to a minimum, by moving the additional wireturns of structures (stubs) B, C to separate planes. This principle maybe more efficient than connecting a number of inductive wire antennas(with all wire ends connected) in series or in parallel. Capacitiveextensions for the antenna A could be formed by creating moreconventional conductive surfaces (plates) to offset the resonantfrequency. An advantage of using wire is ease of creation using wireembedding technology, and better utilization of space. The antennamodule may have very limited space restrictions.)

Various alternatives to the “solution” discussed above may include, butare not limited to

-   -   having the two stubs B and C in the same layer as one another,        but with their turns interleaved with one another,    -   having one or both of the stubs B and C in the same layer as the        antenna A,    -   having the two stubs B and C in the same layer as one another,        but both on the same side of (i.e., overlying or underlying) the        antenna A.    -   connecting the outer end 3 instead of the inner end 4 of the        stub B to the outer end 1 of the antenna A, and connecting the        inner end 6 instead of the outer end 5 of the stub C to the        inner end 2 of the antenna A,    -   having only one stub (B or C) connected by either its outer or        inner end (one only) to the outer or inner end (one only) of the        antenna A, and it may generally be preferred to connect the ends        opposite-wise (outer end of one to inner end of the other),        although connecting likewise (inner end to inner end, or outer        end to outer end) is also possible.

“Quasi-Dipole” Card Antenna (CA)

FIG. 3A illustrates a card antenna 350 in the overall form of asubstantially planar, generally rectangular spiral of wire embedded in acard body (CB, not shown) and comprising two distinct portions (orwindings, or antenna structures, or “poles”) 352, 354, as follows:

-   -   an outer winding (D) having a few turns of wire, an outer end 7        and an inner end 8    -   an inner winding (E) having a few turns of wire, an outer end 9        and an inner end 10        -   note that the inner winding E is shown as a dashed line, for            illustrative contrast with the outer winding D (solid line).    -   each of the outer portion D and inner winding E may have an        overall length of approximately 1200 mm. The inner and outer        winding have substantially the same length as one another.    -   The inner winding E and the outer winding D are both considered        to be “antenna structures” for the card antenna CA. (Compare        “antenna structures” A, B, and C for the module antenna MA.)

The inner winding E and the outer winding D are connect as a “quasidipole” with “reverse phase”. The outer end 7 of the outer winding D isconnected with the inner end 10 of the inner winding E, in any suitablemanner, such as by using a separate jumper or conductive trace withinthe substrate. The connection “j”, is labeled 356, and may simply be anode. The inner end 8 of the outer winding D and the outer end 9 of theinner winding E are left unconnected.

The inner and outer windings E,D may be coupled in close proximity andvoltages induced in the inner and outer windings E,D have opposite phasefrom one another, may be formed in the same layer as one another withthe inner winding E disposed interior of the outer winding D, may beformed in layers overlying each other, substantially aligned with oneanother, may be formed as flat coils of embedded wire, or other thanembedded wire, having a number of turns and an overall length ofapproximately 1200 mm.

The coupling antenna 350 may be formed in a substrate (or card body)using conventional wire embedding techniques (a sonotrode withultrasonic, such as described in U.S. Pat. No. 6,233,818), for exampleas follows:

-   -   start embedding the wire at the position 9 (outer end of inner        winding E) and continue embedding to the position 10 (inner end        of inner winding E), thus forming the few (such as 2, 3 or 4)        turns of the inner antenna winding E    -   stop embedding (turn off the ultrasonics, lift the sonotrode),        and in a next step, route (guide) the wire over the turns of the        inner winding E to the position 7, which will be the outer end        of the outer winding D, without cutting the wire.        -   This jumping over the inner winding E eliminates the need to            have a separate connection bridge or jumper connecting end            10 of the outer winding D with inner end 7 of the inner            winding E. (here, “7” and “10” are positions, not ends.)    -   resume embedding at the position 7 (the outer end of the outer        antenna structure), and continue, forming the few (such as 2, 3        or 4) turns of the outer antenna structure (D), jumping over the        already-laid integral jumper 356 as may be necessary.

As illustrated, a portion “a” of the wire forming the connection “j” maypass over the two (as illustrated) already-laid turns of the innerwinding E, and a portion “b” may pass under the two (as illustrated)to-be-laid turns of the outer winding E. (D), all of this happening atthe bottom of the pattern (essentially a common position vis-à-vis eachof the turns, i.e., at “6 o'clock”). Regarding the wire connection “j”passing under the turns of the outer antenna structure, it will beunderstood that the wire connection “j”. may simply be embedded in thesurface of the substrate (card body), and as the turns of the outerwinding D are laid, embedding temporarily ceases so the turns can jumpover the embedded wire connection “j”. The outer end 9 of the innerwinding E and the inner end 8 of the outer winding D may be left open(not connected with anything).

The portion “b” of the wire connection “j”. which passes under the turnsof the outer antenna structure D may be laid in a channel previouslyformed in the substrate (card body), such as by laser ablation, whichmay obviate the need to turn off the ultrasonics during laying the outerantenna structure to jump over the wire connection “j”.

By connecting the outer winding D and inner winding E in this manner(inner end 10 of inner winding E to outer end 7 of outer winding D, or“reverse phase”), the inner and outer windings are coupled in closeproximity and the effect is additive since the induced voltage of theinner winding E has opposite phase (phase inversion) than the voltageinduced in the outer winding D. Reactive coupling (capacitance andinductance) of the inner winding E and the outer winding D permits thecard antenna CA to be realized with fewer turns than would otherwise bepossible.

The connection of an inner and outer winding (E and D) to form a“quasi-dipole” card antenna exhibiting phase inversion is easilycontrasted with either of U.S. Pat. No. 6,378,774 (Toppan) andUS2009/0152362 (Assa Abloy).

-   -   Note, for example, in Assa Abloy, which discloses two “extremity        sections” 11 and 11′ (corresponding to the outer winding D and        inner winding E), the outer end of the outer extremity section        11 and the inner end of the inner extremity section 11′        (corresponding to the ends or positions 7 and 10 of the card        antenna CA) are left unconnected. The inner end of the outer        extremity section 11 and the outer end of the inner extremity        section 11′ (corresponding to the ends 8 and 9 of the card        antenna CA, which are left unconnected) are connected with a        central section 12 forming at least a small spiral for inductive        coupling with the transponder device (corresponding to the        antenna module AM). Note in FIG. 3A that there is no analogous        coupling coil, coupling is effected by disposing the antenna        module AM directly over (onto) a portion of the card antenna CA,        as discussed in greater detail hereinbelow.    -   Toppan also requires a separate coupling coil (3)

The inner winding E and the outer winding D may be formed as onecontinuous structure, without a separate jumper or trace, usingconventional wire embedding techniques, for example as follows:

-   -   start embedding the wire at the position 9 (outer end of inner        winding) and continue embedding to the position 10, thus forming        the few (such as 2, 3 or 4) turns of the inner winding (E)    -   stop embedding (turn off the ultrasonics, lift the sonotrode),        and in a next step, route (guide) the wire over the turns of the        inner winding (E) to the position 7, which will be the outer end        of the outer winding (D), without cutting the wire. This jumping        over the inner antenna winding E eliminates the need to have a        separate jumper connecting the ends 7 and 10 of the outer and        inner windings. Here, “7” and “10” represent positions        corresponding to respective outer and inner ends of the outer        and inner windings.        -   The portion of wire between positions 7 and 10 may be            referred to as a “connection bridge” or “integral jumper”            356. (And, as mentioned, if the two windings D and E are not            integral with one another, a separate “jumper” would be used            to connect the ends 7 and 10.)    -   after jumping over the inner winding E, resume embedding at the        position 7, and continue, forming the turns of the outer antenna        winding D, jumping over the already-laid connection bridge 356        as may be necessary.        -   Note in the figure that a portion “a” of the connection            bridge 356 passes over the turns of the inner winding E, and            a portion “b” of the connection bridge 356 passes under the            turns of the outer winding D.        -   The portion “b” of the connection bridge 356 which passes            under the turns of the outer winding D may be laid in a            channel previously formed in the substrate (card body), such            as by laser ablation, which may obviate the need to turn off            the ultrasonics during laying the outer antenna winding D to            jump over the connection bridge 356.

The card antenna CA may comprise insulated 80 μm copper wire (Ø: 80 μm),46 mm×76 mm (slightly smaller than the card), pitch of the turns 300 μm,resonant frequency 13.56 MHz.

In combination with a commercially-available chip module (such as NXPSmartMx or Infineon SLE66, or other) which may be specified with aninput capacitance of approximately 10-30 pF the assembled transpondercan be matched to a resonance frequency of 13-17 MHz. See, for example,the following, incorporated by reference herein:

-   -   Product short data sheet, P5CD016/021/041/051 and P5Cx081        family, Secure dual interface and contact PKI smart card        controller, Rev 3.2—March 2011, 20 pages    -   Preliminary Short Product Information, SLE 66CLX360PE(M) Family,        8/16-Bit Security

Dual Interface Controller For Contact Based and ContactlessApplications, Infineon, November 2006, 14 pages

-   -   SLE 66 CX126PE, short Product Overview, May 2010, 4 pages    -   SmartMX for programmable high-security, multi-application smart        cards, NXP, 2009, 2 pages,    -   mifare DESFire Data Sheet Addendum, Preliminary specification,        Revision 2.0, April 2003, 7 pages M086820_MF3ICD40_ModuleSpec

FIG. 3B illustrates, schematically, the card antenna 350 consisting ofan outer winding D and an inner winding E, and is intended as anon-limiting example for describing how the card antenna may function.In this example, the outer winding D has 3 turns modeled by inductancesL1, L2 and L3, and the inner winding E has 3 turns modeled byinductances L4, L5 and L6. All inductances (L) are influenced by thecoupling between all coils. The capacitances C1˜C6 are the coil inherentstray capacitances.

The capacitances C7˜C9 describe the interaction between the two windingsD and E, in case of tight coupling between the inner and outer windings.These additional capacitances reduce the self-resonance frequency of thecard antenna (CA) and may make an additional capacitive componentunnecessary.

The capacitances (C) can be influenced by wire pitch, the inductances(L) by the number of turns.

By way of example, the self-resonant frequency of the card antenna 350is created by the stray capacitance forming between the windings D andE, taken alone without interfering each other). Having only one windingstructure (rather than two) would result in a higher than desiredself-resonant frequency, such as approximately 40˜50 MHz. Theself-resonant frequency may be reduced by (1) increasing numbers ofturns (inductance) or (2) increasing of capacity (reducing wire pitch).Increasing numbers of turns increases inductance and lowersself-resonant frequency. In the case wire ends 8 and 9 are connected and7 and 10 remain open, a standard coil would be formed with the number ofboth wire structures added. This would result in a certain self-resonantfrequency (e.g. 50˜60 MHz). Connecting the windings D and E as shownreduces the self-resonant frequency to approximately 13˜17 MHz with thesame number of turns or length of wire.

Configurations of the Antenna Module AM and Card Antenna CA

The technical attributes of how the module antenna MA of the antennamodule AM interacts with the card antenna CA, and how the card antennaCA may be configured with two windings connected with “reverse phase” toform a “quasi dipole” antenna have been discussed above. Variousparticular configurations (arrangements) for the card antenna CA willnow be described. In each case, the card antenna CA is generally in theform of a rectangular spiral extending around the perimeter of the cardbody CB. In some of the figures, the card body CB may be omitted, forillustrative clarity. The card antenna is intended to work with anantenna module functioning in the contactless mode, including but notlimited to DIF modules, and also including semiconductor chips havingtheir own “on chip” antennas (such as disclosed in U.S. Pat. No.6,373,447).

In all but one of the illustrated configurations described herein (theexception being FIG. 4C), the card antenna CA is in the form of a“quasi-dipole” having two interconnected windings (or “poles”). Thesetwo windings should have substantially the same number of turns, thesame length and the same pitch as one another, and be spaced as closelyas possible to each other over much of their perimeter. They may bewound with the same “sense” (clockwise or anti-clockwise). Variations inany of these parameters (length, pitch, spacing, sense) are of coursepossible, some of which are discussed herein.

FIGS. 4A, 4B show the card antenna CA with an exemplary antenna moduleAM positioned for coupling with the card antenna CA. The antenna moduleAM comprises a DIF chip module CM and module antenna MA for contactlessmode, and contact pads CP for contact mode. A card body CB is providedwith the card antenna CA, which may be a two-winding “quasi-dipole”having an inner winding E and an outer winding D, as described above.(The line “j” designates a connection of the inner end 10 of the innerwinding E with the outer end 7 of the outer winding D, as discussedabove.) The card antenna CA may be formed using 112 μm self-bondingwire, or may be formed as conductive traces using any additive (such asprinting) or subtractive (such as etching) processes.

The antenna module AM is generally rectangular, having four side edges.The module antenna MA is also generally rectangular, having four sideedges. The card antenna CA is also generally rectangular, having fourside edges.

It should be understood, throughout all of the descriptions set forthherein, that the various “rectangular” antenna structures (A, B, C, D,E, MA, CA) will normally have rounded edges, also that the moduleantenna MA may be formed as a round coil or may simply be round or oval.

The antenna module AM is disposed (positioned in the smart card) so thatthe at least one of the four side edges of the module antenna MAoverlaps at least some of the turns of only the inner winding E of thecard antenna CA, for efficient coupling thereto (preferably without alsooverlapping any of the outer winding D). No separate coupling coil isrequired.

The antenna module AM, particularly its module antenna MA, may overlapthe outer winding D rather than the inner winding E. However, it isimportant that the antenna module AM, particularly its module antennaMA, does not overlap both of the inner winding E and outer winding D.

The unconnected ends 8 and 9 of the card antenna CA may be locatednearby each other in the middle between the inner winding E and theouter winding D. Through the connection of the two windings by the wirejumper (or strap), the card antenna forms a resonance circuit for theoperating frequency (approx. 13˜17 MHz).

The connection “j” forces the electrical potential of points (or ends)7, 10 to the same level. When the inner winding E and outer winding Dare exposed to the same magnetic flux of a reader (FIG. 1A), thevoltages of the windings are added. The arrangement of the two windingsis important, and the connection “j” causes a phase inversion and has anadditive effect.

The optimized self-resonance frequency of the card antenna CA may beapproximately 13˜17 MHz, which may create the closest coupling betweenthe card antenna CA and the module antenna MA, resulting in enhanced(increased) read/write distance with respect to an external reader.

The arrangement of the antenna module AM with its module antenna MAphysically overlapping and directly coupling to a two winding cardantenna CA is in stark contrast with U.S. Pat. No. 6,378,774 (Toppan)and US2009/0152362 (Assa Abloy), both of which rely on a separatecoupler coil in addition to a two winding card antenna to effectcoupling with the module antenna. This direct coupling feature of theinvention is attributable to the way the inner winding E is connectedwith the outer winding D so that they are “reverse phased”, andoverlapping the module antenna MA onto only one or the other of theinner and outer windings.

FIG. 4C shows a variation of the card antenna, here designated “F”(rather than CA), having only one continuous coil of wire (rather thantwo windings) and having two ends 11 and 12 which are left unconnected.The antenna module AM with its module antenna MA is positioned tooverlap at least one of the side edges of the card antenna F. In thisillustration, the module antenna MA overlaps all of the turns of thecard antenna F.

Generally, this single winding configuration may require more (such as20) turns of wire to be as effective as the “quasi dipole”configurations which may have only 3 or 4 turns for each of the innerwinding E and outer winding D. More turns require more area, which canbe a problem for smart cards. More turns also results in a stifferantenna structure, which may cause mechanical problems such asmicrocracking in the card body CB. For electronic passports, the singlewinding configuration may be more practical than for smart cards. In anyof the embodiments of card antenna CA disclosed herein, the wire may be“meandering” to address some of these problems.

Coatings, such as in the form of particles or nanoparticles can beapplied to one or both sides of a such as the card body CB. (See FIG.1B, coating 124). Conductive coatings can be applied to formcapacitances, and can be applied to be in contact with portions of theinner E and outer D windings. Such additional capacitances may improveperformance of the card antenna CA. This may be particularly beneficialwith the single winding configuration of FIG. 4C, to reduce the numberof turns required.

FIG. 4D shows a variation of the card antenna, designated CA, which issimilar to the card antenna CA of FIG. 4A, except that here the twowindings E and D are interleaved with one another, rather than the onewinding E being disposed entirely inside of the other winding D. Theends 7, 8, 9, 10 of the windings D and E are comparable to the ends 7,8, 9, 10 of the windings D and E of the card antenna CA of FIG. 4A, andare connected so that the card antenna CA is similarly configured as a“quasi dipole”.

Because of the interleaving of the windings D and E, it is not efficientor effective to overlap only one or the other with the antenna moduleAM.

FIG. 4E shows a variation of the card antenna CA where at least aportion of the inner winding E is spaced further apart from the outerwinding D where the antenna module AM will be overlapping the cardantenna CA. Here, an entire side (right, as viewed) of the inner windingE is spaced farther from the outer winding D than the other three sidesof the inner winding E.

This increased spacing makes it easier to position the antenna module AMso that its module antenna MA overlaps all of the turns of the innerwinding E without overlapping any of the turns of the outer winding D.However, increasing the spacing between the inner winding and the outerwinding may cause some loss of efficiency.

FIG. 4F shows a variation of increased spacing. Here, rather than anentire side of the inner winding E being spaced farther from thecorresponding side of the outer winding D, only a relatively smallportion of the side (here shown as the bottom side) of the inner windingis caused to be farther away from the outer winding D, only where theantenna module AM needs to overlap for coupling of the module antenna MAto the inner winding E of the card antenna CA.

An advantage of this arrangement is preserving the desirable closespacing of the winding E and the winding D over most of the card antennaCA. (The spacing is compromised only specifically where the moduleantenna MA will be interacting with the card antenna CA.)

FIG. 4G illustrates a variation wherein rather than the inner and outerwindings having the same “sense” (such as both anti-clockwise, as inFIG. 4A), the inner and outer windings of the card antenna CA are formedhaving an opposite sense from one another. Here, the outer winding D isformed (from end 7 to end 10) with an anti-clockwise sense, and theinner winding E is formed (from the end 9 to the end 10) with aclockwise sense. Otherwise, the “7/10” connection of the outer end 7 ofthe outer winding D to the inner end 10 of the inner winding E is thesame as before (FIG. 4A), and the inner end 8 of the outer winding andthe outer end 9 of the inner winding E are left unconnected, as before.

Theoretically, a single coil can form a resonant circuit without acapacitor because of the stray capacitance between the windings.However, this configuration may increase the resonance frequency of thecard antenna CA to a level which is not beneficial at 13.56 MHzoperation.

FIG. 4H illustrates a variation wherein the ends of the inner and outerwindings are connected opposite to how the are connected in previousexamples (inner end of inner winding to outer end of outer winding).Based on the “opposite sense” configuration of FIG. 4G, here the innerend 8 of the outer winding D is connected with the outer end 9 of theinner winding, and the outer end 7 of the outer winding D and the innerend 10 of the inner winding E are left unconnected. The connection “8/9”can be made while laying (embedding) the wire, just by making a“U-turn”, so that the card antenna (CA) is one uninterrupted length ofwire (mentioned previously as an alternative to a separate jumperjoining the two windings, in the discussion of FIG. 3A). Alternatively,after laying the outer winding D, from point 7 to point 8, make a U-turnand return interleaved.

This configuration may increase the resonance frequency of the cardantenna CA to a level which is not beneficial at 13.56 MHz operation.

FIG. 4I illustrates a variation wherein the two windings of the“quasi-dipole” card antenna CA are stacked one atop the other, such asone winding F on a top surface of a layer of the card body CB and theother winding G on a bottom surface of the layer. In other words, herethe two windings F and G are in clearly different planes, whereas inprevious embodiments the windings D and E were in substantially the sameplane. As in previous examples, the two windings F and G are similar toone another, and may be connected (not shown) with “reverse phase”.

Recalling that it is desirable for the antenna module AM to interact(via its module antenna MA) with only one of the two windings of the“reverse phase” connected “quasi dipole” card antenna CA, this resultmay be obtained by providing a shielding material, such as ferrite,between the module antenna MA and the winding of the card antenna CAdesired to be shielded, while the other winding of the card antenna CAis not shielded. This can be accomplished by providing ferrite particlesin the card body CB, at least at the location where the antenna moduleAM will be positioned atop the card body CB. Alternatively, a layer offerrite material could be disposed between the top surface of the cardbody CB and the winding F, below the top winding F . This allows for andmay also tend to increase coupling of the module antenna MA with thewinding F on top of the card body CB, while attenuating coupling withthe winding G below the card body CB.

The thickness of the substrate determines the permeability and thereforethe efficiency of the coupling effect between the two windings F and G.The dielectric medium may be a polymer like polycarbonate or Teslin™.

FIG. 4J illustrates another example of shielding one of the two windingsof a “quasi-dipole” card antenna CA. In this case, the windings may beinner and outer, as described with respect to FIG. 4A, and both disposedon the top surface of the card body CB. The inner winding E is interiorthe outer winding D.

A shielding material such as ferrite may be selectively applied over theouter winding D at a location where the antenna module AM may otherwiseinteract with the outer winding D.

Additional ferrite material may be applied under the card body CB at thesame location to further minimize undesirable coupling of the antennamodule with the outer winding D.

In these “shielding” embodiments of FIGS. 4I, 4J, the shielding materialshould only be applied at a location on the card body CB or the bottomor outer winding (G or D, namely the winding with which it is sought tominimize coupling with the module antenna MA), and it should generallybe avoided to shield the remaining majority of the bottom or outerwinding (G or D) since the bottom or outer winding serves an importantrole in coupling with an antenna of an external contactless reader(refer to FIG. 1A).

Additional Configurations for the Card Antenna CA

In the various configurations described hereinabove, the card antenna CAis substantially in the form of a planar, rectangular spiral (with theexception of the configuration in FIG. 4I where two planes areestablished), and one side edge of the antenna module AM overlaps atleast a portion of the card antenna CA, generally only one of the twowindings thereof. Some additional configurations for the card antennafor improving coupling will now be described wherein (generally)

-   -   (i) the antenna module AM may overlap the outer winding D        (rather than the inner winding E) of the card antenna CA    -   (ii) two or more edges of the antenna module AM may overlap one        (or the other) of the two windings (D or E) of the card antenna        CA    -   (iii) two or more antenna modules may be provided in the smart        card, each interacting with the card antenna CA, and possibly        with each other.

In the embodiments described below, antenna modules AMs will be shown ona card body CB with “simplified” showings of the card antenna CA. Somedetails, such as the interconnection of ends of the inner and outerwindings may be omitted, for illustrative clarity.

It should be understood that any suitable contactless (or DIF) antennamodule AM (or chip module, or chip with integrated antenna) may be usedto interact with the exemplary configurations for the card antennas CA,including commercially-available antenna module products which may onlythe antenna A (without the capacitive stubs B, C).

The various patterns for antenna structures (A,B,C,D,E) are shown as“generally rectangular”. It should be understood that other patterns maybe suitable, such as oval to avoid sharp corners, or zigzag (meandering)to increase the overall length of the antenna structures, alleviateincreasing stiffness of the card body CB, and the like.

FIG. 5A shows an embodiment of a card antenna CA having an inner windingE and an outer winding D on a card body CB. A first antenna module AM1is disposed to overlap the inner winding E of the card antenna CA at oneside (right, as viewed) thereof, and may be a DIF antenna module such ashas been described above.

Generally, at least a portion of the module antenna MA overlaps at leasta portion of the card antenna CA for coupling thereto without theintermediary of a coupling coil associated with the card antenna CA.Here, one side of a rectangular-shaped module antenna MA is shownoverlapping the inner winding E of the card antenna CA. The moduleantenna MA may have another shape, such as round or oval, and it mayoverlap the outer winding D rather than the inner winding E. In someembodiments disclosed herein, the overlap between the module antenna MAand the card antenna CA is increased such as by overlapping two sides ofa rectangular module antenna MA with the selected portion of the cardantenna CA.

A second antenna module AM2 having its own module antenna MA is disposedto overlap the inner winding E of the card antenna CA at another side(left, as viewed) thereof, and may be a contactless only antenna modulefor multi-application transponders, providing additional security, andthe like. Both of the antenna modules AM1 and AM2 are coupled to thesame, inner winding E of the card antenna CA, and can communicate witheach other as well as with an external reader (see FIG. 1A).

FIG. 5B shows an example of coupling two side edges of an antenna moduleAM3 to the card antenna CA. Here, the antenna module AM3 is disposed ata corner of the rectangular card antenna CA, such as the top rightcorner so that the top and right side edges of the antenna module AM3overlap the a portion of the top and right edges of the inner winding E.This is a suitable location for a contactless-only (ISO 14443) antennamodule AM3. Locating a DIF antenna module with contact pads at thislocation on a smart card may be prohibited by other prescribed formfactors (such as embossing areas).

Two-edge coupling of the module antenna MA to the card antenna CA mayprovide greater coupling than one-edge coupling (other factors beingequal).

FIG. 5C shows another example of coupling two side edges of the antennamodule AM to the card antenna CA. Here, the card antenna CA deviatesfrom rectangular in that in the upper right corner (as viewed) it anglesin from the top edge of the card for a distance, then angles out to theright edge of the card body CB, these two right angles resulting in an“L-shaped” path (jog, cutout) at the upper right hand corner of the cardantenna CA, approximately the size of an antenna module AM.

In the previous example of FIG. 5B, the antenna module AM3 was in theupper right corner of the smart card, and could not have a contactinterface. Here, the antenna module AM can be disposed midway up thecard body CB, the same as in any FIGS. 4A, 4C, 4D, 4G, 4H, 5A, and cantherefore suitably be a DIF antenna module having contact pads. (Asecond contactless only antenna module, not shown, could be disposed inthe top right corner of the card body CB, where it would be coupled withthe outer winding D to provide additional features, as discussed abovewith respect to FIG. 5A.)

FIG. 5D shows a configuration wherein the card antenna CA deviates fromrectangular in that it has a “U-shaped” jog (or cutout) comprising tworight angles, extending inward from the right edge of the card antennaCA, midway up the card body CB, suitable shaped and sized to accommodatean antenna module AM disposed midway up the card body CB which and cansuitably be a DIF antenna module having contact pads. In FIG. 4A theantenna module AM couples with the inner winding E, in FIG. 5D theantenna module AM couples with the outer winding D.

Whereas the configuration of FIG. 5C enabled coupling 2 sides of theantenna module AM with the card antenna CA, the “U-shaped” cutout allowsfor coupling 3 sides of the antenna module AM with the card antenna CA,and a consequent increase in coupling efficiency. In this configuration,the antenna module AM overlaps the outer winding D rather than the innerwinding E.

A second antenna module could be added in the manner of FIG. 5A (AM2),the second antenna module being coupled with the other, inner winding E.Recall that these couplings are relevant primarily to the contactlessmode, and coupling each of two antenna modules to different ones of thetwo coupling antenna windings (D or E) may provide additionalcapability.

FIG. 5E shows a configuration wherein the card antenna CA deviates fromrectangular in that it has a “U-shaped” projection extending outwardfrom the right edge of the card antenna, midway up the card body CB,suitable shaped and sized to accommodate an antenna module AM disposedmidway up the card body CB which and can suitably be a DIF antennamodule having contact pads. Contrast with FIG. 5D which has an inwardjog and the antenna module AM is disposed external to the card antennaCA, coupling with the outer winding D. Here, the card antenna CAprojects outward, the antenna module AM is disposed interior to the cardantenna CA and couples with the inner winding E.

This configuration provides for 3-side coupling of the antenna module AMwith the inner winding E of the card antenna CA. (Recall that theconfiguration of FIG. 5D also provided for 3-sided coupling, but withthe outer winding D.)

An advantage illustrated by this configuration is that a given antennamodule (AM1) may be coupled with the inner winding E and another givenat least one antenna module can readily be located for coupled with theouter winding D, in either of the “L-shaped” cutouts.

FIG. 5F shows a configuration wherein the card antenna CA deviates fromrectangular in that it has a “U-shaped” projection extending outwardfrom the right edge of the card antenna, midway up the card body CB, ina manner identical (for discussion purposes) to the a “U-shaped”projection in FIG. 5E, and similarly, a DIF antenna module AM1 isdisposed in the projection.

This figure illustrates that an additional antenna module AM2 can bedisposed midway up the card body CB, on the left side of the cardantenna CA, and can suitably be a second DIF antenna module havingcontact pads. Additionally or alternatively, a third antenna module AM3can be disposed in the upper right corner (as shown) of the card antennaCA, outside of the card antenna CA, so as to couple with the outerwinding D of the card antenna CA. Alternatively, the third antennamodule AM3 or yet another antenna module could be disposed in the lowerright corner of the card antenna CA.

The ease with which additional antenna modules (AM2, AM3) may beincorporated, simply by overlapping the card antenna CA at a differentlocation than the first antenna module (AM1) illustrates anotherprofound difference with Assa Abloy or Toppan, either of which wouldrequire an additional coupling coil for each of the additional antennamodules.

FIG. 5G is a diagram showing an upper right corner of a card body CBwith a card antenna CA. The outer winding D (solid lines) has 4 turns ofwire, and is close to the exterior edge of the card body CB. The innerwinding E (dashed lines) has 4 turns of wire, is located inside of theouter winding D, towards the interior of the card body CB. Someconsiderations in configuring the card antenna CA include . . .

-   -   in this example, the module antenna MA overlaps the inner        winding E    -   The two windings E, D may have substantially the same number of        turns (such as 3 or 4, each), the same length and the same pitch        as one another, and be spaced as closely as possible to each        other over much of their perimeter. The spacing between the        outermost turn(s) of the inner winding E and the innermost        turn(s) of the outer winding D should be maintained as close as        possible, in order to maximize the reactive coupling.    -   the card antenna CA may be fine-tuned (resonance frequency        adjusted) altering the pitch of the outermost turns of the outer        winding D (compare U.S. Pat. No. 7,928,918, Gemalto)    -   the outermost turn(s) of the inner winding E should be as close        as possible to the innermost turn(s) of the outer winding D for        effective coupling of the two windings E, D

FIG. 5H illustrates a configuration for the card antenna CA similar toFIG. 5C. Only two turns for each of the inner E and outer D windings areshown, for illustrative clarity (typically they would have 3 or 4 turns,each). Instead of an “L” shaped jog formed with right angles (FIG. 5C),the inner E and outer D windings follow a more “gentle” arcuate(curving) path, including a radiussed portion where a circular moduleantenna MA will overlap the inner winding E, such as with 90-degrees ofits circumference (compare coupling with one or more edges of arectangular module antenna MA, as discussed above). Generally, theobjective is to cover as much overlapped surface area as possiblebetween the card antenna CA and the module antenna MA. Thisconfiguration illustrates an antenna module AM with a round moduleantenna MA, and the card antenna CA is patterned to provide anopportunity for substantial overlap at an appropriate location on thecard body CB. Some other considerations in configuring the card antennaCA include . . .

-   -   the connected ends or positions 7, 10 should be as close        together as possible    -   the turns of the winding can be spread slightly to accommodate        the free ends 8, 9 ends which are located in the middle of the        card antenna CA.    -   create a channel in the substrate for the connection “j” by        laser ablation or milling    -   note that the ends 8, 9 are in the middle separating the inner        winding E from the outer winding D. This “wire break” should be        maintained as small as possible so that the innermost turns of        the outer winding D and the outermost turns of the inner winding        E are maintained in close proximity with one another.

An Application for a Contactless RFID Tag

To direct the flux field emanating from a high frequency RFID tag, aferrite layer with high magnetic permeability can be integrated into anintermediate layer of a card body, with said layer hosting an area ofresin with magnetic fillers, ferrite nanoparticles in a polymer or asheet of sintered ferrite, for the purpose of reducing eddy currentlosses and to decouple the RFID tag from an underlying metal surfacesuch as the metal casing of a battery in a mobile telephone. Thisshielding in the HF band prevents attenuation of the carrier wave (13.56MHz) caused by inducing eddy currents on the metal surface of thebattery. Without shielding, the eddy currents create a magnetic fieldreversing the direction of the carrier wave.

FIG. 6A illustrates a cell phone 650 having a display and a keypad onits front surface (facing down in the figure), and containing a batterypack (“battery”). A contactless RFID device (“tag”) 660 is disposed onthe back (top, as viewed) surface of the phone. The tag 660 has anantenna 662 inside for interacting with an external RFID reader 680. Theantenna 662 may be a conventional antenna integral with the tag. Thereader 680 also has an antenna 682 associated therewith, typically muchlarger than illustrated.

The tag 660 is exemplary of a mobile phone sticker (MPS) which may beused for e-payment, e-ticketing, loyalty and access controlapplications.

A ferrite (or other suitable material) shielding element 670 is disposedbetween the back of the cell phone 650 and the tag 660 to alleviateattenuation of coupling between the tag and the reader. The element maybe in the form of a film or tape, and may have adhesive on both sidesfor sticking the contactless tag to the phone. Double-sided tapes havingadhesive on both sides are well known, such as for mounting carpets.

FIG. 6B shows the ferrite shielding element 670 may comprise:

-   -   a core layer (or substrate) 672 which may be in the form of an        elongate tape measuring a few centimeters wide and having two        surfaces and having ferrite (or other) particles (including        nanostructures) dispersed throughout    -   an adhesive layer 674 on a bottom (as viewed) surface of the        tape    -   an adhesive layer 676 on a top (as viewed) surface of the tape,        and    -   a release layer 678 which will be peeled off and discarded,        protecting the top adhesive layer 676.

The shielding element is suitably delivered in roll form, similar tocommon double-back adhesive tape, and the release layer prevents thebottom adhesive layer 674 from sticking to the top adhesive layer 676when the shielding tape 670 is rolled up (in roll supply form).

Some Manufacturing Processes

FIG. 7A illustrates a first step in an exemplary manufacture andassembly of an antenna module (AM) comprising:

-   -   copper foil with gold, nickel or palladium plating,    -   module tape (MT) such as conventional “super 35 mm” tape    -   super 35 mm tape. Holes may be provided through the tape, for        connecting from the opposite side of the tape to the underside        of the foil, such as with plated through holes (PTH)

FIG. 7B illustrates a further step in the manufacture and assembly ofthe antenna module (AM). The foil is laser etched to have a number (suchas six) of contact pads (CP) for contact interface. This is the familiarterminal block of contacts seen on many bank cards and the like. On theopposite side of the tape, not visible, a chip module CM and moduleantenna MA will be provided.

FIGS. 7C, 7D illustrate the opposite side of the module tape MT. (Inthis view, the contact pads CP are not visible.) Plated Through Holes(PTH) and some interconnects are visible. A DI chip may be mounted tothe module tape MT and wire bonded to the plated through holes PTH andinterconnects. A module antenna MA may be mounted and connected.Glob-top (a conformal coating of resin) may be applied to protect thedie and wire bonds, the module antenna MA acting as a dam for theglob-top. Alternatively, the module antenna MA can be mounted onto themold mass (glob-top) of the antenna module AM as a flat antennastructure.

A ferrite layer may be provided, as discussed hereinabove (FIG. 1D, 156)with holes for interconnects (such as wire bonds). FIG. 7C illustrates(right side) that an opening (FIG. 1D, 158) may be provided through theferrite layer to accommodate the die.

FIG. 7E shows a DI smart card formed using the antenna module of FIG.7D, on a card body (CB) having a card antenna (CA).

Channels can be formed in a substrate such as the card body CB foraccepting a wire (or conductive material) laid therein. (for example,U.S. Pat. No. 7,028,910—Schlumberger). A recess can be formed foraccepting the antenna module AM. (See FIGS. 1A, 7E). Channels andrecesses can be formed in a substrate using laser ablation.

FIG. 7F illustrates the antenna wire extending into, across the bottomof, and emerging out of the recess for accepting the antenna module AM(FIG. 7E). Only a relevant portion of the card body CB and only one turnof the antenna wire are shown, for illustrative clarity. Thisfacilitates minimizing the distance between the module antenna MA andthe card antenna CA when the module antenna MA is implanted in the cardbody CB, the close proximity ensuring effective coupling of the moduleantenna MA with the card antenna CA.

While the invention(s) has/have been described with respect to a limitednumber of embodiments, these should not be construed as limitations onthe scope of the invention(s), but rather as examples of some of theembodiments. Those skilled in the art may envision other possiblevariations, modifications, and implementations that are also within thescope of the invention(s), based on the disclosure(s) set forth herein.

1. A smart card comprising: an antenna module (AM) comprising at leastone chip or chip module (CM) and a module antenna (MA); a card body (CB)having at least one surface and a periphery; and a card antenna (CA)extending around the periphery of the card body (CB); characterized inthat at least a portion of the module antenna (MA) overlaps at least aportion of the card antenna (CA) for coupling thereto without theintermediary of a coupling coil associated with the card antenna (CA).2. The smart card of claim 1, wherein: the card antenna (CA) comprisestwo windings (D,E) connected in reverse phase with one another; and theantenna module (AM) overlaps only one of the two windings (D,E) forcoupling thereto.
 3. The smart card of claim 1, wherein the card antenna(CA) comprises: an outer winding (D) having an outer end (7) and aninner end (8); an inner winding (E) having an outer end (9) and an innerend (10); the inner end (10) of the inner winding (E) is connected withthe outer end (7) of the outer winding (D); and the inner end (8) of theouter winding (D) and the outer end (9) of the inner winding (E) areunconnected.
 4. The smart card of claim 1, wherein: the card antenna(CA) is formed with jogs or cutouts for maximizing overlap of the moduleantenna (MA) with the card antenna (CA).
 5. The smart card of claim 1,further comprising: additional one or more antenna modules (AM2, AM3)overlapping the card antenna (CA).
 6. The smart card of claim 1, wherein(FIG. 2A) the module antenna (MA, 200) comprises: a first antennastructure (A) in the form of a coil having first and second ends (1,2);a second antenna structure (B) in the form of a coil having first andsecond ends (3,4); a third antenna structure (C) in the form of a coilhaving first and second ends (5,6); the first end (4) of the secondantenna structure (B) is connected with the first end (1) of the firstantenna structure (1) and to a first terminal of the chip module (CM),the second end (3) of the second antenna structure (B) is leftunconnected; and the first end (5) of the third antenna structure (C) isconnected with the second end (2) of the first antenna structure (1) andto a second terminal of the chip module (CM), the second end (6) of thethird antenna structure (C) is left unconnected.
 7. The smart card ofclaim 1, further comprising: ferrite material disposed on or in the cardbody for enhancing coupling of the module antenna (MA) to the cardantenna (CA).
 8. The smart card of claim 1, wherein the antenna module(AM) further comprises: contact pads (CP) for a contact mode ofoperation.
 9. The smart card of claim 8, further comprising: a ferriteelement (FE) for decoupling the module antenna (MA) from the contactpads (CP).
 10. The smart card of claim 9, wherein: the card antenna (CA)is patterned to increase overlap between the module antenna (MA) and theselected portion of the card antenna (CA).
 11. A method of coupling achip module (CM) having at least a contactless mode to a card antenna(CA) disposed on a card body (CB) of a smart card, comprising providinga module antenna (MA) in an antenna module (AM) with the chip module(CM), characterized by: providing the card antenna (CA) as “quasidipole” antenna having two winding portions connected in reverse phasewith one another.
 12. The method of claim 11, wherein: the card antenna(CA) has an inner winding (E) and an outer winding (D); and the moduleantenna (MA) overlaps only one of the inner and outer windings (E, D).13. The method of claim 11, wherein the chip module (CM) is a dualinterface (DI) chip module having contact pads (CP), further comprising:ferrite (FE) disposed between the module antenna (MA) and the contactpads (CP).
 14. The method of claim 11, wherein the module antenna (MA,200) comprises: a first antenna structure (A) in the form of a coilhaving two ends (1,2); a second antenna structure (B) in the form of acoil having a first end (4) connected with one end (1) of the firstantenna structure (A), and a second end (3) left unconnected; and athird antenna structure (C) in the form of a coil having a first end (5)connected with another end (2) of the first antenna structure (A), and asecond end (6) left unconnected: the second and third antenna structuresforming capacitive stubs for the first antenna structure (A).
 15. Themethod of claim 11, further comprising: patterning the card antenna (CA)to maximize overlap with the module antenna (MA).